Many herbicides injure crop plants by slowing crop plant growth and development at herbicide application rates necessary to control weed growth. Accordingly, many herbicides cannot be used for controlling weeds in the presence of certain crops. Reduction of herbicidal injury to crops without an unacceptable corresponding reduction of herbicidal action on the weeds can be accomplished by use of crop protectants (also known as "herbicide antidotes" or "safeners"). A new class of crop protectants is provided by 1-phenylthio-1-cyclopropanecarbonitrile and substituted phenylthio derivatives thereof.
Preparation of 1-phenylthio-1-cyclopropanecarbonitrile, by reaction of .alpha.-phenylthioacetonitrile with ethylene dibromide, is described in a publication of Makosza et al [Tetrahedron Letters, No. 23, pp. 2391-2394 (1972)]. There is no suggestion that the cyclopropanecarbonitriles shown in the Makosza publication are useful as crop protectants.